# Rate limiting zones
limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;
limit_req_zone $binary_remote_addr zone=general_limit:10m rate=50r/s;
limit_conn_zone $binary_remote_addr zone=conn_limit:10m;

# Upstream servers
upstream explorer_api {
    server 127.0.0.1:8080;
    keepalive 32;
}

upstream explorer_frontend {
    server 127.0.0.1:3000;
    keepalive 32;
}

# Redirect HTTP to HTTPS
server {
    listen 80;
    listen [::]:80;
    server_name explorer.d-bis.org www.explorer.d-bis.org;
    
    # Allow Let's Encrypt validation
    location /.well-known/acme-challenge/ {
        root /var/www/html;
    }
    
    # Redirect all other traffic to HTTPS
    location / {
        return 301 https://$server_name$request_uri;
    }
}

# Main HTTPS server
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name explorer.d-bis.org www.explorer.d-bis.org;

    # SSL Configuration (Cloudflare handles SSL, but we can add local certs too)
    # ssl_certificate /etc/letsencrypt/live/explorer.d-bis.org/fullchain.pem;
    # ssl_certificate_key /etc/letsencrypt/live/explorer.d-bis.org/privkey.pem;
    # ssl_protocols TLSv1.2 TLSv1.3;
    # ssl_ciphers HIGH:!aNULL:!MD5;
    # ssl_prefer_server_ciphers on;

    # Security headers
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;

    # Content Security Policy (adjust as needed)
    # CSP: unsafe-eval required by ethers.js v5 UMD from CDN
    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.jsdelivr.net https://unpkg.com https://cdnjs.cloudflare.com; style-src 'self' 'unsafe-inline' https://cdnjs.cloudflare.com; img-src 'self' data: https:; font-src 'self' data: https://cdnjs.cloudflare.com; connect-src 'self' https://api.cloudflare.com https://explorer.d-bis.org wss://explorer.d-bis.org https://rpc-http-pub.d-bis.org wss://rpc-ws-pub.d-bis.org http://192.168.11.221:8545 ws://192.168.11.221:8546;" always;

    # Logging
    access_log /var/log/nginx/explorer-access.log combined buffer=32k flush=5m;
    error_log /var/log/nginx/explorer-error.log warn;

    # Client settings
    client_max_body_size 10M;
    client_body_timeout 60s;
    client_header_timeout 60s;

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_min_length 1000;
    gzip_types
        text/plain
        text/css
        text/xml
        text/javascript
        application/json
        application/javascript
        application/xml+rss
        application/rss+xml
        font/truetype
        font/opentype
        application/vnd.ms-fontobject
        image/svg+xml;

    # Brotli compression (if available)
    # brotli on;
    # brotli_comp_level 6;
    # brotli_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

    # Frontend
    location / {
        limit_req zone=general_limit burst=20 nodelay;
        limit_conn conn_limit 10;

        proxy_pass http://explorer_frontend;
        proxy_http_version 1.1;
        
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Port $server_port;
        
        proxy_cache_bypass $http_upgrade;
        proxy_read_timeout 300s;
        proxy_connect_timeout 75s;
        proxy_send_timeout 300s;
        
        # Buffering
        proxy_buffering on;
        proxy_buffer_size 4k;
        proxy_buffers 8 4k;
        proxy_busy_buffers_size 8k;
    }

    # API endpoints
    location /api/ {
        limit_req zone=api_limit burst=20 nodelay;
        limit_conn conn_limit 5;

        proxy_pass http://explorer_api;
        proxy_http_version 1.1;
        
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header Connection "";
        
        proxy_read_timeout 300s;
        proxy_connect_timeout 75s;
        proxy_send_timeout 300s;
        
        # Disable buffering for API responses
        proxy_buffering off;
        
        # CORS headers (Cloudflare will also add these)
        add_header Access-Control-Allow-Origin "*" always;
        add_header Access-Control-Allow-Methods "GET, POST, OPTIONS" always;
        add_header Access-Control-Allow-Headers "Content-Type, X-API-Key, Authorization" always;
        
        # Handle preflight
        if ($request_method = OPTIONS) {
            add_header Access-Control-Allow-Origin "*";
            add_header Access-Control-Allow-Methods "GET, POST, OPTIONS";
            add_header Access-Control-Allow-Headers "Content-Type, X-API-Key, Authorization";
            add_header Access-Control-Max-Age 1728000;
            add_header Content-Type "text/plain; charset=utf-8";
            add_header Content-Length 0;
            return 204;
        }
    }

    # WebSocket support
    location /ws {
        proxy_pass http://explorer_api;
        proxy_http_version 1.1;
        
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        proxy_read_timeout 86400s;
        proxy_send_timeout 86400s;
        proxy_connect_timeout 75s;
    }

    # Static files caching
    location ~* \.(jpg|jpeg|png|gif|ico|css|js|svg|woff|woff2|ttf|eot|webp|avif)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        add_header X-Content-Type-Options "nosniff";
        access_log off;
        log_not_found off;
    }

    # Health check endpoint (internal only)
    location /health {
        access_log off;
        proxy_pass http://explorer_api/health;
        proxy_set_header Host $host;
    }

    # Block access to sensitive files
    location ~ /\. {
        deny all;
        access_log off;
        log_not_found off;
    }

    location ~ \.(env|git|gitignore|md|sh)$ {
        deny all;
        access_log off;
        log_not_found off;
    }
}